Abstract: In order to compare the difference in the undrained shear strength parameters of the residual granitic soil samples obtained by different test methods, the undisturbed residual granitic soil samples from an offshore wind farm in Putian, Fujian Province were performed with the laboratory unconsolidated undrained direct shear tests, the consolidated undrained shear tests, the unconsolidated-undrained (UU) triaxial compression tests, the consolidated-undrained (CU) triaxial compression tests. The objective of these tests was to study undrained shear strength parameters obtained from different test methods. The results show that the consolidation has a significant effect on the undrained shear strength. The cohesion c and the internal friction angle φ obtained by the sample sheared after consolidation are greater than those under the unconsolidated condition; the sample depth has a great effect on the cohesion c measured by the direct shear tests and UU tests; the internal friction angle φ_cu and the effective internal friction angle φ'_cu of the CU tests increase with the increase of the sample depth, and the effective cohesion φ'_cu decreases with the increase of the sample depth; the cohesion c obtained by the direct shear tests with the same depth and consolidation conditions is smaller than the triaxial tests, and φ is much larger than the triaxial tests.

Key words: Residual Granitic Soils, Direct Shear Tests, Triaxial Tests, Undrained Shear Strength Index